Current Research

Thursday, February 26, 2009

Walk Like A Modern Human: 1.5 Million-Year-Old Footprints Found In Ileret, Kenya

Fossilized footprints were found between two sedimentary layers in Ileret (Rutgers' Koobi Fora Field School), Kenya that dates back about 1.5 million-years-ago. These footprints show that its owner was walking upright, bipedally and the foot already had the anatomy like those of modern humans: relatively adducted hallux (big toe), medial longitudinalarch and medial weight transfer before push-off. The size of the footprints corresponds to the stature and body mass of Homo ergaster, an earlier version of Homo erectus (Bennett et al., 2009).

Cover of Science, 27 February 2009. Optical laser scan of early hominin footprints at Ileret, Kenya, color-rendered to illustrate depth; reds indicate areas of high elevation, blues lower elevation. The footprints are 1.5 million years old and were probably made by Homo ergaster/erectus. Two right footprints and a partial left are visible along with a range of animal prints. Image processing in RapidformTM: Matthew Bennett/ Bournemouth University.

These footprints are distinct from the "famous" Laetoli footprints, discovered by Mary Leakey in 1976 at Laetoli, Tanzania which dates to about 3.5 million-years-ago. The Laetoli footprints belong to Australopithecus afarensis and at least two individuals were present, walking side by side.

The Ileret footprints are different and similar to the Laetoli footprints in many ways. Laetoli footprints are more ape-like, Ileret footprints are more human-like. Both, however, do not have an opposable toe like those of chimpanzees. Both footprints indicate that its owner was walking bipedally or has a bipedal gait.

Comparison between a chimpanzee footprint and Australopithecus afarensis (Laetoli) footprint. Photo of chimpanzee footprint from www.elucy.org and photo of Laetoli footprint from www.columbia.edu